On killing mundanes
by Quecksilver Eyes
Summary: It doesn't feel right. There's an itch under her skin and never enough wetness washing around her and her fin splits and forms legs. She wants to scream, wants to sink her claws into the flawless skin that is so different to her hard upper body, covered in scars, covered in every name the mundanes have ever given her kind. mermaid AU


Mundanes are not to be killed unless necessary. Any violator is to be persecuted and punished. No exceptions are to be made.

When Isabelle sees mundanes for the first time, her throat aches and her fins quiver. There's blood under her nails and the scent of death in her nostrils. The mundanes stare at her and she stares back, claws digging into the cliffs. She starts singing, throat glowing, scales shimmering in the sunlight. "Come to me", she sings. "Come to me and I shall give you everything you desire." The blood smells sweet and her fangs break the skin on her lips. The mundanes steer the boat towards her and the hunger in the pit of her stomach intensifies. Water flows around her gills and then suddenly there's skin under her claws and strength in her fin and she pulls.  
The mundane doesn't scream as she sinks her fangs into his flesh and stills her burning hunger.

"You will go", her queen says, hair flowing around her, throat glowing. Isabelle bows her head and sinks her fangs into her lower lip. She nods and her gills ache and she wishes she could just dissolve into sea foam, just like her youngest sister, who lost all her laughs and her voice to a mundane and who lost herself in the end, who jumped into the water with a smile on her lips and the sea took her back like the lost daughter she was. But Isabelle just nods and dreads the feeling of her fin shedding its scales, of her fangs withdrawing into her gums, of her gills closing up, of breathing air.  
It doesn't feel right. There's an itch under her skin and never enough wetness washing around her and her fin splits and forms legs. She wants to scream, wants to sink her claws into the flawless skin that is so different to her hard upper body, covered in scars, covered in every name the mundanes have ever given her kind. But there are no claws anymore, the webs between her fingers have disappeared and when she stands up, she falls back to the ground.  
Her legs are too weak to carry her, swimming has not strengthened the muscles she needs for walking. We shouldn't walk dry ground just because it's possible, she once told her sisters. It's blasphemy, what more do you need than the sea. She wants to crawl back into the sea, wants to have her claws and her fangs and her fin. She doesn't. She pulls herself up and tries standing again.  
When she finally learns to walk, bloody footprints are the only thing left on the ground.

Seelies cannot lie. They are beautiful, they are cunning, they speak in riddles and they do not trust shadowhunters. Her sisters whisper encouragements in the back of her head as Isabelle puts on the dress Magnus Bane has laid out for her. It clings to her body like water, flows around her curves and she smiles at him. Thank you, she smiles. Thank you for giving me a little bit of home. He just waves his hand and tells her to always cover her throat. The necklace he gifted to her centuries ago lies heavy on her chest. She smiles and misses her fangs. Magnus brushes her hair and starts colouring it. Seelies do not like natural hair colours. "That's a prejudice", she says and tells him about the seelie girl who knew Isabelle's body the way it was, who used to whisper praise into her scars. She never coloured it, she never smiled unreadable smiles. Magnus shrugs and tells her about the clave.  
Isabelle wants to go home.

When she arrives at the institute, hair dyed a bright red to match the ruby in her necklace, chest moving rapidly, feet in high heeled pumps, she faces a glowing seraph blade and pale skin covered in runes. The shadowhunter's red curls remind her of fire and she wishes she still had her fangs hidden behind red lips, just to feel a little safer. "Take the shoes", Magnus said, "they will make you feel better." They do. The heel is long and sharp and reminds her of her claws, the constant clacking on the pavement makes her think about her sisters who use their fangs to navigate in the deepest pits of the ocean. _Oh Mother Sea,_ she thinks, _let me be strong._  
"Who are you", they ask, skin covered in angelic runes, hands hovering over knives and bows and whips. She holds her head high, shows the pride she earned with every name the mundanes gave her. "My queen sent me", she says and her red lips curl into a smile. The lipstick is the exact colour of fresh blood and it makes her straighten her back and tell the lies her queen laid into her mouth, carefully clad in double negatives and hypothetical statements.  
They don't let her stay at the institute. She's an official from the seelie queen, she says and demands they show her the restrictions made in the Accords. Find a loophole, her queen whispered. Save your kind.  
 _Oh Father Tides, let me be brave._

Isabelle's feet hurt when the shadowhunter with the red curls smiles at her and tells her that she needs to come with her. "I'm gonna give you a tour", she says and Isabelle wonders if the runes on her pale skin will hurt her, if she can cup her hips in the palms of her hands. She looks so breakable.  
Her name is Clary and Isabelle tells her that she wears too many clothes. Clary laughs. "They told us seelies were honest." Isabelle smiles and takes the glass of water Clary hands her. The water makes her feel a little more secure and she sits down and crosses her legs. Clary puts her seraph blade on the table and starts telling her stories. She doesn't give her a tour in the end and Isabelle's skin itches and her feet hurt and she wants nothing more but to sing sweet agony into Clary's curls.  
"Do not fall in love", her sisters whisper. "It'll break your heart and you will loose your voice." _You will turn into sea foam_ , Isabelle thinks and looks at Clary's neck. A rune stretches along her skin and Isabelle wants to trace it with her fingertips. Her sense of smell doesn't work, her balance is put off by the slightest of changes and she wishes she could just crawl into a bath tub and feel the water wash all the blood off of her. Clary puts her hair up and stretches. She is tired, she says, but Isabelle cannot listen. Her eyes are drawn to the rune on her pale neck, to the curve of her collar bones and the soft line of her jaw. Hr fingers twitch and oh, how she misses her fangs. They would remind her of her place, of her heart that should not be put into another's hands, of a soul that will never be hers and of burning hunger in the pit of her stomach.  
She stays in a guarded room that night and feels like the treasures her sisters sing about.

She runs into Magnus, on the next day. His hands are tight around the shadowhunter's waist, eyes locked onto his lips. She smiles and tells him to have fun. The shadowhunter looks confused. She just laughs and when he asks her what she means, she hides the truth behind complicated sentence structures and possibilities. Magnus sways back and forth.  
Her heels clack onto the floor with every step she takes and her mind tells her that there is something wrong with the sound. She ignores it. It is used to water, where everything sounds softer and deeper and more like a melody. The training room is covered in runes and Clary is fighting against a blonde nephilim, blades crossing, bodies moving swiftly, sweat staining their shirts. Isabelle's breath hitches in her throat as he throws her to the ground and she wishes she still had her claws just to tear him apart. She can feel her back hunching and her fingers curling but Clary just laughs. It's a silent laugh and her nose twitches and Isabelle freezes. "Don't follow your instinct", Magnus said as he dyed her hair. "Seelies do not let emotions control them."  
"We are nothing but emotions", she told him and thought about the seelie girl arching her back, Isabelle's claws on her skin.  
That's the worst thing about it, she thinks. Standing there and smiling and talking when her skin itches and her anger burns close to the surface.  
Clary lets the shadowhunter help her up and they continue training. Isabelle straightens her back and walks to the head of the institute. "I need to see the Accords", she says, carefully wrapped in the seelie's complicated way of speaking.  
 _Show me the Accords._

There is no loophole. _Mundanes are not to be killed unless necessary_ , it reads. And, in a footnote, _if mundane flesh or blood is required for nourishment, the respective leader is expected to find a suitable alternative._  
Isabelle does not cry. She smiles at Clary and cleans the blood off her high heels and tells Magnus that there was nothing to misunderstand in the first place. Magnus smiles sadly and offers a glass of alcohol. She declines and tells her queen the same thing. She scowls and tells her to try harder. _Save your kind, my sister._  
Isabelle holds her head high and asks Magnus for a place to stay. He looks at her, cat eyes glowing, a dark hickey on his neck and offers her a flat with a big tub. She smiles and thanks him, feels the lipstick sticking to her skin and gives him her necklace. He just portals her into the flat.

The first night Isabelle spends behind walls that are not guarded, she pours salt into the tub and lets water flow into it and when the whole flat is rich with the scent of salty water, she steps into the tub, relishes in the feeling of her fin and her gills and her claws and her fangs. The webs in between her fingers stick to the cold surface of the tub and she curls into a tiny ball and breathes water again.  
She doesn't turn off the tap when she falls asleep and she didn't plug the tub, so there's a constant stream of fresh water against her gills and for the first time in a week, she feels a little more at home.  
The tub is not a permanent solution. Her back hurts and her mind keeps screaming for space and swimming and nourishment. Her stomach is tied into a knot and she ignores it, just like the urge to offer her voice to Clary.

Clary smiles and holds up her hands. "I'm not armed, I swear." Isabelle feels her fingertips quiver as she steps aside. The skin on her throat is clear to see and she bites down on her lower lip hard enough to draw blood. She searches through her necklaces for something to cover it so she can speak again while Clary takes in her surroundings. Isabelle finds a neckband and puts it on, a little tighter than strictly necessary just so she remembers who she is. "Hello", she says and Clary plays with her curls and smiles.

The runes do burn her but Isabelle finds herself leaning into Clary's touch. She is used to boiling hot springs hidden under the sea's gentle surface, she's used to the cold waters and the pitch black. Clary's hair seems to glow against the white fabric of the pillow and Isabelle loses herself in touching and feeling and sucking dark marks onto Clary's pale skin. Clary sighs and writhes and arches her back and Isabelle cups her hips into the palms of her hands and whispers praise into the runes.  
She never takes off her neckband and when Clary comes undone, mouth agape, neck stretched, hands clutching onto the sheets, Isabelle wants to offer her voice.  
"Izzy", Clary mumbles into Isabelle's skin that is hidden beneath glamours. "Beautiful, wonderful Izzy."

Months later, when Clary's first stop after a mission is Isabelle's apartment and Isabelle knows every inch of her body, she takes off her neckband. "I need to show you something", she says. Clary leans back and furrows her brows.  
Isabelle sings, throat glowing, glamours falling. She shows Clary each name she earned, and washes the colour out of her hair. Clary remains silent, her fingers trace tiny patterns onto Isabelle's skin. "You lied to me", she says. Isabelle straightens her back and Clary's fingers brush one of the names on Isabelle's rib cage. "Tell me the stories behind them", she says. "Please, Izzy."  
Isabelle takes off her high heels and tells Clary of each and every one of them. Clary paints a beautiful meadow onto Isabelle's skin and Isabelle arches her back and sighs.

Blue is a very dominant colour in the Institute. Isabelle didn't notice the first time, she was too busy keeping up a cover and trying, trying, trying to do something that couldn't be done. It doesn't make her think of home. Water is not blue, it is brown and green and black and sometimes it's as red as Clary's curls. She misses the sea. She doesn't miss her sisters, who do not know how to mourn.  
The trial is torturous. It is half lies and accusations and rune covered skin threatening to tear her apart. "You impersonated an advocate", they say, "you are guilty of personality theft." Isabelle holds her head high and tells her story, bending the truth to protect her sisters and her queen. "I wasn't sure about the Accords anymore", she says. "I was hungry."  
"You must not kill mundanes", they say. "I know", she answers, ice in her voice and dread in the pit of her stomach. She thinks about the sailors and her sisters, thinks of the burning hunger that itches under her skin.  
"You can survive up to a decade without food", they say and Isabelle keeps silent. There are so many of us, she wants to say. There's so much hunger and so little to feed off. Give us an alternative.  
 _Save your kind, sister mine._

Clary fights for Isabelle's freedom, runes dark against her skin, red curls in a neat bun, beautiful lithe body hidden beneath a blazer and Isabelle wants to give her her voice, wants to give her the world.  
Later, when Isabelle lies in her cell and Clary was allowed to see her one last time, and red curls tickle Isabelle's skin, she cries out Clary's name, throat glowing brightly. Clary's fingertips brush over it and Isabelle whimpers. "It's yours", she says. "Take it." Clary smiles, on the verge of crying and Isabelle sings for her.

"Let's run away", Clary says, later, when Isabelle finishes singing, when the hunger in her stomach lessens and the tip of Clary's stele glows. Isabelle smiles and nods, thinks about swimming and fins and fangs and claws.  
Clary draws a rune onto the door and hell breaks loose.

Isabelle takes Clary's hands, soft and secure, as her legs turn into her tail again as she sheds the last glamour. She smiles a fanged smile and Clary shivers. Isabelle brushes her red curls out of her face and whispers praise into her runes. "I failed", Clary says. "I was supposed to protect mundanes."  
"You did", Isabelle says and tells Clary about the hunger in her stomach that vanished when Clary took her voice, tells her about envy and immortality.  
Clary jumps into the water and clings onto Isabelle's waist, no sign of fear on her face and later, when Isabelle's claws trace her runes, when Magnus offers protection, when Isabelle feels home again, Clary says Isabelle's name like a prayer.

 _Izzy. I love you, Izzy._


End file.
